1. Field of the Invention
This invention relates to a pn-junction device of a II-VI group compound semiconductor, and in particular to a LED (Light Emitting Diode) for blue light and a method of manufacturing the same.
2. Description of the Prior Art
Conventionally, LEDs of II-VI group compound semiconductor have been comprised, as is shown in FIG. 4, of layers of n-type ZnSe and p-type ZnSe stacked on a n-type GaAs substrate. This has been described, for example, in Abstract, The 6th International Conference on Molecular Beam Epitaxy, Aug. 8, 1990, San Diego School, California University, No. PIV-31. In such a device, electric current flows from p-type ZnSe and through n-type ZnSe to reach an n-type GaAs substrate.
With the structure as described above, however, sufficient light emission is not obtained due to incoincidence of the junction surface of the conduction band of n-type ZnSe and n-type GaAs. In addition, sufficient light emission is not obtained due to the low carrier-density of Li-doped p-type ZnSe.